{"id":48,"date":"2007-05-29T09:48:12","date_gmt":"2007-05-29T08:48:12","guid":{"rendered":"http:\/\/www.ozone3d.net\/blogs\/lab\/?p=48"},"modified":"2011-09-07T20:47:23","modified_gmt":"2011-09-07T19:47:23","slug":"glsl-ati-vs-nvidia","status":"publish","type":"post","link":"https:\/\/www.ozone3d.net\/blogs\/lab\/20070529\/glsl-ati-vs-nvidia\/","title":{"rendered":"GLSL: ATI vs NVIDIA"},"content":{"rendered":"

Today two new differences between Radeon and Geforce GLSL support.<\/p>\n

1 – float2 \/ vec2
\nvec2<\/b> is the GLSL type to hold a 2d vector. vec2<\/b> is supported by NVIDIA and ATI. float2<\/b> is a 2d vector but for Direct3D HLSL and for Cg. The GLSL compilation for Geforce is done via the NVIDIA Cg compiler. Here is the GLSL version displayed by GPU Caps Viewer<\/a>: 1.20 NVIDIA via Cg compiler<\/b>. That explains why a GLSL source that contains a float2<\/b> is compilable on NVIDIA hardware. But the GLSL compiler of ATI is strict and doesn’t recognize the float2<\/b> type. <\/p>\n

2 – the following line:<\/p>\n

\r\nvec2 vec = texture2D( tex, gl_TexCoord[0].st );\r\n<\/pre>\n
is valid for NVIDIA compiler but produces an error with ATI compiler. One again, the ATI GLSL compiler has done a good job. By default, texture2D()<\/b> returns a 4d vector. The right syntax is:<\/p>\n
\r\nvec2 vec = texture2D( tex, gl_TexCoord[0].st ).xy;\r\n<\/pre>\n
Conclusion: always test your shaders on both ATI and NVIDIA platforms unless you target one platform only. <\/p>\n","protected":false},"excerpt":{"rendered":"
Today two new differences between Radeon and Geforce GLSL support. 1 – float2 \/ vec2 vec2 is the GLSL type to hold a 2d vector. vec2 is supported by NVIDIA and ATI. float2 is a 2d vector but for Direct3D HLSL and for Cg. The GLSL compilation for Geforce is done via the NVIDIA Cg compiler. Here is the GLSL version displayed by GPU Caps … Continue reading GLSL: ATI vs NVIDIA<\/span> »<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9,8],"tags":[22,172,171,18,51,173],"class_list":["post-48","post","type-post","status-publish","format-standard","hentry","category-opengl","category-programming","tag-ati","tag-cg","tag-compiler","tag-glsl","tag-nvidia","tag-texture2d"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t